There have been known two types of prior art characteristic value identification methods and apparatuses therefor in the following:
One is disclosed in the Japanese Patent Application No.6-140081, No. 8-18946, No. 9-287161, and the like. This prior art method adopts means for identifying a natural frequency, a natural mode, and a modal damping ratio based on measured data of a frequency response function (FRF) obtained by a vibration test of a tested object (part).
The other is a method called a characteristic matrix identification method. This method adopts means for identifying three kinds of characteristic matrices, i.e. a mass matrix, a damping matrix, and a stiffness matrix, which are coefficients of an equation of motion formulated based on “equilibrium of forces” rule in a dynamics system, from time history measured data of an exciting force and a response obtained by the vibration test of the tested object (part).
Generally, a machine has a mechanical power source generating a kinetic energy in some way, and is composed of a large number of parts such as a mechanism which transmits the mechanical power and a mechanism which takes advantage of the mechanical power for the work. Also, with the parts composing the machine, parts based on a physical unit system such as electric, mechanical, and fluid systems are organically united or combined.
The fact is that models which reproduce such a large number of parts with many different theoretical backgrounds are individually modeled for the identification according to the physical unit system in which the parts are included or the application thereof, with a mutual theoretical relationship being neglected regardless of high generality of the individual part and mechanism. For this reason, it has been disadvantageous that the above-mentioned two types of prior art based on the techniques of the mechanical system can be applied only to a specific phenomenon of mechanical system vibration.
Also, in the prior art, the model (part) has been identified only by one dimension “strength (flow quantity)” for two dimensional quantities “quantity (potential quantity)” and “strength” which prescribe energy. Namely, since both rules which govern each of the two kinds of quantities composing energy are not applied, continuity of velocity and acceleration has not been represented on the identified model, so that it was disadvantageously difficult to unite the parts with each other.
Furthermore, since the prior art only expresses a structure of a model, i.e. a positional relationship of the characteristics composing the model but not the functions of the characteristics, structural phenomena which the characteristics are compounded to reveal, e.g. a natural frequency, a natural mode shape, or a characteristic matrix of an entire structure can only be made clear by the identification, so that it has been impossible to directly clarify the characteristic values governing the function of an object.